Abstract
The Precambrian tectonic architecture of the East Antarctic Shield is subject to considerable uncertainty because of limited outcrop. The Fisher Terrane, located in the central region of the Prince Charles Mountains, evolved during the Mesoproterozoic as a volcanic arc system and provides key data about the evolution of this region. Our study provides evidence that the Fisher Terrane formed in proximity to a Proterozoic plate boundary and was subsequently metamorphosed during the late Neoproterozoic to early Cambrian during the final stages of Gondwana amalgamation. U–Pb detrital zircon geochronology reveals that metasedimentary rocks from within a metasedimentary–metavolcanic package cropping out at Fisher Massif were deposited after c. 1300 Ma, and contain detritus derived from the Rayner–Eastern Ghats Terrane. This suggests that the Fisher Terrane was not an isolated oceanic arc but rather formed on the same tectonic plate as the Rayner Complex. Metapelitic schists from within the same metasedimentary package yield metamorphic U–Pb monazite ages of c. 512–509 Ma, corresponding to a regionally recognized Pan-African-aged event. This event has not been previously identified in the Fisher Terrane, and demonstrates that Pan-African-aged metamorphism affected all parts of the Prince Charles Mountains. Calculated phase equilibria modelling constrains the metamorphic conditions during this event to 2.5–4.0 kbar and 550–615°C, corresponding to apparent thermal gradients of 146–220°C kbar −1 . Such conditions plausibly relate to metamorphism taking place in an extensional setting. Supplementary material: Methods and summarized mineral chemistry data, sample locations, U–Pb zircon and monazite data, and representative electron microprobe mineral analyses are available at https://doi.org/10.6084/m9.figshare.c.4392710
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.